1. Field of the Invention
This invention relates to an imaging optical system for effecting photography of an object image in a photographing apparatus, particularly an apparatus such as a telescope or a microscope which enables the object image by an objective lens to be observed through an eyepiece.
2. Description of the Prior Art
As a method of effecting telephotography by the use of a telescope, for example, an interchangeable eyepiece type telescope used for the observation of wild birds or a shooting target, it is known to move the eyepiece and use it as a relay lens. That is, as shown in FIG. 1 of the accompanying drawings, the spatial image I by an objective lens L.theta. is enlarged and projected onto a film surface F by an eyepiece Le moved from a usual position, namely a position for observation by the naked eye, thereby effecting telephotography of an object. However, according to this method, photography is effected through an eyepiece originally designed for observation by the naked eye and therefore, aberrations such as chromatic aberration, curvature of image field, distortion, etc. have been great and there has been a marked difference in quality of image as compared with a telephoto lens exclusively for use for photography.